Beam compass



` March 13, 1928.

r E. LAWRENZ BEAM COMPAS S Fil'ed May 20, 1.927

Patented Mar. 13, 1928.

UNITED STATES EMIL LAVVRENZ,l OF DETROIT, MICHIGAN.

BEAM COMPASS.

Application filed May 20,

This invention relates to instruments usually known as beam compassesor trammels for scribing circles ot larger diameter than can be conveniently drawn by means of ordinary compasses, and its object is to providel an instrument of this character which shall be light, which shall be rigid, and which can be accurately adjusted.

This 'invention consists in the detailsl orn construction illustrated in the accompanyingdrawing and particularly pointed out in the claims. u y

In the drawing- Fig. 1 is a side elevation et my improved beam compass;

Fig. 2 is a longitudinal vertical section oit the head provided with removable legs;

Figs. 3 and si are sections on the lines 33 y and 4l-l ot F ig. 2 respectively.

Similar reference characters referto like parts throughout the several views.

The beam i is preferably formed with rounded upper and lower edges so that the slots in the heads may have rounded upper and lower walls to conserve strength and stilt'ness. It desired, the weight oi the beam may be reduced by grooving the sides which will not atleet the strength thereof to any appreciable extent. The body of the tram head 2 is formed with an upwardly projecting stem 3 which is threaded to receive the milled unit e, and slidable on this stem is a clamping member 5 provided with two pins 6 which engage the beam, these pins extendn ing through holes 7 in the body of this head parallel to the stem 3 and along its longitudinal plane. I prefer these pins to be round so that the holes that receive them will affect the strength of this head as little as possible. These two pins enable me to get a maximum et gripping action on the beam for a. minimum of pressure by the nut.

The tram head 2 is longitudinally grooved in its lower edge to produce the flanges 9, between which the tram point carrier 10 is pivoted on the pin 1,1 carried by these flanges. rIhe head and the point carrier are recessed to receive the spring 12. A pin 13 extending across the groove 11i in the head 2 extends through the head 15 in the adjusting screw 16 which is threaded to receive the nut 17. The adjacent end of the point carrier 10 is formed with a vertical groove 18 to receive the reduced portion 19 of this nut, a circular flange 2O on the upper end oi" this reduced portion and a circumferen- 1927. Serial No. 192,840.

tial Shoulder 21 at the lower end thereof being in engagement with the upper and lower faces of the adjacent flanges produced by this groove 1S.4 The point carrier may theretore beswung on the pivot'll by turning this nut 17 in either direction andA its threaded end 29. This leg is longitudinally split at its lower end and bored to 1'eceire a pencil 30, a screw 31 being provided to cause the two sides to grip the pencil. llenor pin legs may be used in the saine manner but'these legs do not involve any' part ot' the present' invention.

The tram head 33 is provided with a stational-y leg or trampoint carrier 34 which is grooved in the usual manner to receive the point 35 which passes through a'loop 36 on the bolt 37 on which the nut 38 1s threaded to Secure the point in position. The locking p mechanism for this head is similary to that for head 2. Y v

I claim 1. In a beam compass, the combination of a beam and a tram head Slidable thereon,

means to secure the head to the beam, said head being formed with a groove in its lower .,side, a pivot extending across one end of said groove, a tram-point carrier mounted on said pivot, a trampoint extending down from said carrier, a Second pivot pin extending across the opposite 'end of said groove, a holt mounted thereon, and a nut on said bolt engaging the adjacent end oi' the point carrier and adapted to move said carrier to swing said leg. f

2. In a beam compass, the combination o'l a beam and a tram head slidable thereon, means tovsecure the head to the beam, said head being orm'edvwith a groove in its lower side, a pivot extending across one end of said groove, a train-point carrier mounted on said pivot, a" train-point extending down from said carrier, a second pivot pin extending across the opposite end of said groove, a bolt mounted thereon, and a nut on said belt enno v f faeing the adjacent end of the point carrier and adapted to move said Carrier to swing said leg'-A and a spring' between said head and `arrier to take up all slaclmess between the carrier. mit and bolt.

3. ln a beam compass, a beam and a` tram head provided with a slot to receive said heam. said head havingr an upwardly 'extendin;r threaded stem and holes in its central plane parallel to said stem, a clamp slidable on the gutem and having pins extending into Said holes and into engagement with said beam. a mitA on said stem adapted to force said clamp inwardly.r and a point carrier projecting from the bottom of Said head.

l. In a beam compass, a beam and a tram head provided with a Slot to receive said beam. said head havin;r an upwardly projecting stem and openings adjacent thereto, a mit. on said stem and a clampingr member slidahle on the stem and having projections Leeg-315 adapted to extend into said openings into engagement with said beam, and a point carrier projecting from the bottom of said head.

5. In a. beam compass, the comliination of a beam and a tram head slidable thereon. means to secure the head to the beam. said head being,r formed with a groove in its lower side. a pivoty extendingr across one end of said groove, a tram-point; carrier mounted on .L4-.iid pivot, a tram-point; extending down .from said carrier,y a Second pivot; pin e:\:t,endin;r across the opposite end of `said groove, a bolt mounted thereon, and a mit on said holt. en-

gaging the adjacent end of the point carrier and adapted tio move said carrier to swing said lejl. Said mit having a redneed cyliinlri- Lal portion with Shoulders at the ends'` thereo'l', and Said point arrier havin;r a notch to receive said reduced portion of the mit'. th(l Walls of Said notch engaging said shoulders.

EMIL LAXVREN.. 

